when taking out my old 305tbi (LO3) and putting a new zz383 crate, what are somethings to take care of? Like do I need a completely new computer, or have the original one reprogramed with my new setup? All the sensors that are on my LO3, such as the colling fan switch, coolant temp sensor, egr valve and sensor, basically all the computer controlled saftey sensors, where would they go? any mods to the suspension or frame to support a slightley heavier engine? etc... stuff like that.

Thanks,

The engine won't be heavier. Any suspension mods would be due to the increased power & torque.

The rest of your questions involve TBI, so I'll move this to that forum.

just swap all the sensor to there respected location on the new motor and get a prom flashed for the new setup

Ohhh if only it was that simple.....a proper tune can NOT be made from a list of mods. You may be able to get away with a mail order tune on the newer LS vehicles, but the simplicity of the older TBI computers makes this impossible. The only way to maximize the new engine is to custom tune the chip to the motor, you can do this yourself or pay big bucks to have some one else do it for you. Check out my "free tune" sticky and see if DIY tuning is for you. There are quite a few 383 threads on the boards, it would do you good to read them all and decide if you are willing to go through the work required.